1. Field of the Invention
This invention relates to a device for absorbing torque fluctuations. The invention is particularly useful in a motor vehicle or vessel equipped with an engine which during operation, has wide torque fluctuations at its output, such as a diesel engine.
2. Description of the Prior Art:
A typical device of the type to which this invention pertains is disclosed in Japanese Patent Publication No. 1497/1985. This patent publication discloses a first flywheel attached to the output shaft of an engine and a second flywheel which is concentric with the first flywheel. A bearing, spring mechanism and a slip mechanism are provided between the first and second flywheels. The first and second flywheels have a specific relation to each other with regard to the moment of inertia and cooperate with the spring mechanism to absorb vibration when the engine is rotating at a high speed. When the engine is rotating at a low speed, the slip mechanism absorbs excessive torque which is due to sympathetic vibration.
The slip mechanism of the prior art, however, is designed for actuation at a considerably high level of torque corresponding to a practically useful range of high rotating speeds which are at least equal to the idling speed of the engine. In order to absorb vibration effectively when the engine is rotating at a low speed, however, it is important to lower as far as possible the torque which is transmitted to the second flywheel. It is, therefore, necessary to lower the torque which the slip mechanism is designed for absorbing, or narrow the range of rotating speeds giving rise to a high level of torque, in order to diminish or absorb vibration effectively.